(i) Technical Field
The present invention relates to a belt, and, particularly, to a belt suitable as an intermediate transfer belt and as a sheet conveyer belt that are used in image forming devices such as electrophotographic copying machines and printers, and to an image forming device provided with the belt.
(ii) Related Art
In image forming devices such as copying machines and printers utilizing a electrophotographic system, an electrostatic latent image formed on the surface of an image carrier by known electrophotographic processes is developed on the image carrier to form a toner image thereon. Then, this toner image is transferred electrostatically onto a recording medium using a transfer device, thereafter the toner image is fixed onto the recording medium, for example, by means of a heat fixing mechanism, to form an image.
When a belt is used in the transfer device that transfers the toner image onto the recording medium, the belt is trained over plural tension rolls and rotated in a predetermined running direction, thereby enabling conveying of the recording medium in a circulating manner. In transfer devices of such type, a phenomenon may occur, so-called belt walk, wherein the belt is shifted in the direction of the axis of the tension rolls, due to the dimensional tolerance of component parts constituting the transfer device or variation in parallelism and outer diameter of the tension rolls. If the image forming device is driven when this belt walk is present, the belt may be wrinkled, causing image unevenness, or even break.
On the other hand, an intermediate transfer type transfer device is used as the transfer device in some cases, from the viewpoint of advantages in conveying of paper, and the like. A system of intermediate transfer type has already been proposed, in which toner images of respective color components are sequentially formed on the image carrier, then the toner images of respective color components are primarily transferred onto the intermediate transfer body temporarily, thereafter the transferred multilayer toner images formed on the intermediate transfer body are secondarily transferred onto the recording medium, collectively, and thereby a color image is obtained. As the intermediate transfer body, one in the form of a belt or drum is commonly used. When a belt is used as the intermediate transfer body, belt walk may occur, as is the case of the aforementioned transfer device not using the intermediate transfer body.
Also, a belt having elasticity is used as the belt to meet the needs for higher quality image and operation speed, in some cases. Generally, in image forming devices using an elastic belt, the elastic belt is used in an expanded manner. Therefore, when a member forming a rib is attached to the elastic belt, it is more likely that the rib is peeled off than in the case where a resin belt is used, due to differences in thermal expansion coefficient, elastic modulus or the like, between the belt, adhesive and the rib.